Studies on flower structure and fertilization biology of black mulberry (Morus nigra L.)

In this thesis, it is aimed to designate the flower structures of black mulberry and to examine the fertilization biology. The research was carried out in the black mulberry population in and around the province of Tokat. Phenological observations were made in the genotypes in the determined population, the morphological characteristics of the flowers, their pollen performance were examined. Different pollination applications were made, and the morphological characteristics of the fruits obtained from these applications were determined. In the studied population, it was determined that 49% of the trees were monoicous, 43% dioecious female, 6% dioecious male and 2.5% mixed structure of inflorescence. In most of the monoicous trees, although the inflorescences consist entirely of male or female flowers, there were also trees in which both female and male flowers can coexist in the same inflorescence, albeit in a small number, and they were defined as mixed. It was determined that the length of the inflorescences of male flowers ranged from 42.7 to 19.88 mm and of female flowers from 24.1 to 8.21 mm. Abnormal flowers with undeveloped female organs were also found on the female inflorescences. The number of flowers in a cluster varied between 26.4 and 10.6 in male inflorescences and between 52.0 and 13.5 in female inflorescences. The number of pollen in an anther was determined as 51666 in Genotype 28 and 54666 in Genotype 5. Pollen viability rates were 90.4% in Genotype 28 and 89.2% in Genotype 5. Pollen germination rates were determined as 72.9% in Genotype 28 and 68.7% in Genotype 5. In controlled pollination studies, it has been observed that black mulberries can form a high rate of parthenocarpic fruit without pollination and fertilization. It has been determined that there was a great variability in the number of seeds formed in a cluster under both artificial pollination and free pollination conditions. Significant positive correlations were found between the number of seeds formed in a cluster and fruit weight and fruit size.